Conservation of angular momentum in RRKM theory. A three-dimensional model for nonlinear molecules

Abstract

The “usual” implementation of the unimolecular rate constant in RRKM theory treats nonlinear molecules as pseudo-diatomics and thus does not conserve total angular momentum. A three-dimensional model for conservation of total angular momentum for vibrator transition states in the K rotational quantum number either active or adiabatic is presented and a comparison made between this model and the “usual” one in the low-pressure limit for two different reactions. This showed that the three-dimensional model resulted in significantly larger rate constants when the K rotor was active, indicating the importance of conservation of total angular momentum.